Anesthesiology and Risk Assessment Quiz

Preoperative Assessment

• Preoperative visits are essential for safe and successful anesthesia.
• The aim of preoperative assessment is to identify medical and anesthetic risks to reduce morbidity and mortality.
• Anesthetic drugs and techniques have profound effects on human physiology.
• A focused review of all major organ systems is needed before surgery.
• The goal of preoperative evaluation is to ensure the patient is in the best condition possible.
• Patients with unstable symptoms should be postponed for optimization prior to elective surgery.
• Emergent surgery in unstable patients requires careful consideration of risks versus benefits.

Objectives

• Evaluate and optimize the patient's medical condition.
• Plan anesthetic technique and peri-operative care.
• Develop rapport with the patient to reduce anxiety and facilitate anesthesia.
• Allow appropriate discussion between patient/guardian and medical staff.
• Obtain informed consent.

Definition of Timing of Surgery

• Emergent: Required when life or limb is threatened without immediate surgery.
• Urgent: Procedure is required within 24 hours.
• Semi-Urgent: Condition where disease progression is undesirable (e.g., cancer), and should be addressed as soon as possible.
• Elective: Surgery can be scheduled without time constraints.

Classification of Operation (NCEPOD)

• Immediate: To save life, limb, or organ; target time to theatre - within minutes (e.g., major trauma with uncontrolled hemorrhage).
• Urgent: Acute onset or deterioration of condition threatening life or limb/organ; surgery when resuscitation is complete (e.g., compound fracture, perforated viscus).
• Expedited: Stable patient needing early intervention; target time to theatre - within days (e.g., closed fractures, some tumor surgeries).
• Elective: Surgery planned and booked in advance; all conditions not covered in categories 1-3 (e.g., joint replacements, cholecystectomies).

Key Components of Preoperative Assessment

• Problem Identification: Focused history, examination, review of investigations, and response to treatment.
• Risk Assessment: Plan of anesthetic technique (pre-operative, intra-operative, post-operative).

General Principles

• Personnel: preoperative clinic visit by medical staff.
• Place: appropriate setting.
• Timing: patient's condition is considered.
• Preoperative admission: patient undergoes necessary procedures/tests.
• Multi-disciplinary management: all relevant departments involved.
• Emergency surgery: addressed quickly.

Process of Preoperative Evaluation

• History (including review of medical records)
• Physical examination
• Laboratory evaluation
• Prediction of perioperative morbidity and mortality
• Documentation (informed consent, preoperative note).

Preoperative History

• Presenting condition and concurrent medical history, (e.g., bowel cancer, malnutrition, anemia, electrolyte imbalance).
• Coexisting medical conditions (e.g., cardiovascular, respiratory, angina, previous MI, heart failure, hypertension, preexisting lung disease, rheumatoid disease, diabetes, renal disease).

Assessment of Capacity of Cardiorespiratory System

• Metabolic equivalent (MET) levels: ratio of metabolic rate during a physical activity to resting metabolic rate.
• MET score correlates with activity levels from light housework to strenuous exercise.

NYHA Classification

• Class I: No limitation of physical activity.
• Class II: Slight limitation of physical activity.
• Class III: Marked limitation of physical activity.
• Class IV: Unable to carry out any physical activity without discomfort.

Medication History

• Generally, most long-term medications should be continued up to the morning of surgery, but this needs discussion with surgeon.
• Drug interactions need to be considered.
• Previous surgical procedures and anesthetic history: documented.
• Exposure to specific anesthetic agents should be avoided if contraindicated (e.g., halothane).
• Family history with focus on potential problems, like prolonged apnea, malignant hyperthermia.

Medications That May Interact With Anesthetic Agents

• ACE inhibitors (ACEIs) have synergistic interactions with anesthetics causing hypotension.
• Antibiotics increase neuromuscular blocking effect.
• Anticoagulants increase hemorrhage risk.
• Anticonvulsants and benzodiazepines have additive effects with CNS depressants.
• Beta-blockers have negative inotropic effects that can worsen hypotension.
• Calcium channel blockers may increase the effects of inhalational agents.
• Diuretics can cause hypokalemia, potentially prolonging neuromuscular blockade.

Social History

• Smoking: nicotine triggers tachycardia, hypertension, CO reduces O2 carriage, and stops 6-12 weeks before surgery for optimal effects.
• Alcohol: may induce liver enzyme induction, increasing the minimum alveolar concentration (MAC) needed for an anesthetic.

Physical Examination

• Nutritional state and fluid balance.
• Blood pressure.
• Heart sounds.
• Respiratory status.
• Airway assessment.
• Nervous system assessment.

Anatomical Factors Associated With Difficult Laryngoscopy

• Short, muscular neck.
• Protruding incisors ("buck teeth").
• Receding lower jaw.
• Poor mobility of mandible.
• Decreased atlanto-occipital distance (requires X-ray).

Mallampati Classification

• Classifies airway suitability.

Thyromental Distance (TMD)

• Measurement from thyroid cartilage to chin.
• Normal distance is greater than 6.5 cm.

Sterno-mental Distance (SMD)

• Measurement from manubrium to chin.
• Normal distance is greater than 12 cm.

Inter-incisor Distance

• Distance between incisors, measured with maximal mouth opening.
• Greater than 4 centimeters is considered normal.

Cormack-Lehane Classification

• Visualization of laryngeal aperture (I-IV).

Upper Lip Bite Test

• Classifies mandibular movement.

Mandibular Protrusion Test

• Classifies how far lower incisors can protrude.

LEMON Rule

• Method to assess airway.

Quick Airway Assessment

• Assess the patient's ability to open their mouth, protrude their tongue, move their jaw forward, and fully turn/extend their neck/head.

Predictors of Difficulty to Face Mask Ventilate (OBESE)

• Obese patients.
• Bearded patients
• Elderly patients.
• Snoring.
• Patients with no teeth (edentulous).

Laboratory Evaluation

• Only necessary investigations should be performed.
• Healthy, minimally invasive procedures might not require extensive lab tests.

Routine Investigations for Asymptomatic Patients

• Age and type of surgery determine required tests.

Investigations for Patients With Abnormal Clinical Findings

• Investigations based on specific abnormal indications.

Period of Validity of Tests

• Varies based on test (blood work is usually 1 week; ECG is usually 1 month; chest X-ray is typically 6 months).

Risk Assessment

• Patient's medical condition before surgery.
• Extent of surgical procedure.
• Risk from the anesthetic.

"Clear the Patient for Surgery"

• A summary for the approval of a patient for surgery.

Prediction of Perioperative Morbidity and Mortality (ASA)

• This chart helps to predict the risks associated with surgery.
• Categorizes patients based on physical health status.
• Mortality rates are associated with each class.

Goldman's Cardiac Risk Index

• Risk factors for cardiac problems during surgery.
• Uses a point system.

Risks According to Type of Surgery

• Based on the type of operation, risk factor tables are provided.
• Categorized into low, intermediate, and high-risk surgeries.

Postponing Surgery

• Situations that warrant delaying surgery.

Preoperative Fasting Guideline

• Guidelines on how long before surgery various foods are to be discontinued/not eaten by a patient.

Documentation (Informed Consent)

• Informed consent includes reasonable explanation of options, sufficient information on procedures, risks, written consent, history, physical examination, laboratory results, consultant recommendations, and anesthetic plan.

Stages in the Consent Process

• A summary of the steps for a patient to understand the procedures, risks, and consent their choices under physician guidance.

Discuss type of anesthetic, time for decision

• Emphasize the importance of the patient understanding and having time to make decisions.

Period of Validity of Consent

• Consent is valid until the patient's condition changes.
• When the patient's condition or need for the procedure changes, a new consent must be obtained.

Elements of Valid Consent

• Capacity to consent.
• Sufficient information.
• Voluntariness in decision-making.

Factors for Selection of Anesthetic Technique

• Safety of patient.
• Preexisting systemic disorders.
• Site of operation.
• Age of patient.
• Patient preference.
• Anaesthetist ability.

Preaesthesic Routine Preparation

• Provide psychological support/reassurance to a patient.
• Perform patient fasting requirements.
• Ensure patients are void before surgery.
• Verify patient's false teeth removal, absence of lip/eye make-up or nail polish.
• Confirm proper identification labeling.
• Obtain mandatory consent.
• Administer premedication as needed.

Premedication

• Administration of drugs within 1-2 hours before induction.
• Objectives: induce anxiolysis and amnesia, prevent aspiration, and counteract autonomic effects.
• Drug groups include those to decrease anxiety or induce amnesia, prevent vomiting, counteract autonomic responses and provide analgesia, e.g., benzodiazepines, antidepressants, anti-emetics etc.
• Types and doses of pre-medication vary based on patient indications.

Aspiration Prophylaxis

• Indications: pregnancy, morbid obesity, large abdominal mass, hiatus hernia, and gastro-esophageal reflux.
• Interventions include antacids - sodium citrate, H2 antagonists - ranitidine and cimetidine, proton pump inhibitors - omeprazole and pantoprazole and prokinetics - metoclopramide.

Plan of Anesthesia

• Local or regional anesthesia with standby monitoring and/or sedation.
• General anesthesia with or without intubation (spontaneous or controlled ventilation).
• Combined regional with general anesthesia.

Suitable Anesthetic Techniques For Different Types of Surgery

• Different types of surgeries require different anesthetic techniques (local, regional, or general).

Further Review

• The review of the patient's entire medical history, current conditions, and other relevant details as indicated.

Other Topics

• Preoperative checklist points for surgery that involves the face, head and neck, abdominal region, upper and lower limbs, groin, perineum,
• Potential complications.